This document relates to an electrical switch and, more specifically, to a single-pole, single-throw switch which may be used as a detect switch in a motor vehicle, e.g., in association with a door latch.
Electrical switches have been designed for selectively establishing at least a first conductive way between two conductive fixed contacts, the switch having a housing and a pushbutton arranged such that when an external force is applied to the pushbutton, the pushbutton is moved relative to the housing between a first position in which the conductive way is established and a second position in which the conductive way is interrupted. This conductive way (and, thus, the switch) can be of the normally-open (NO) type or of the normally-closed (NC) type.
According to a known design, such a switch might be of the “snap switch” type, such as those illustrated in U.S. Pat. No. 2,743,331 and/or U.S. Pat. No. 3,098,905. In such a design, the switch has a high current carrying capacity and a relatively long life duration. However, the “snapping” or “clicking” noise present in such a switch may be detrimental in some applications, and a hysteresis may be present. A snap switch also has a limited over travel capacity.
According to another known design, the switch might be of the “slide switch” type, such as that illustrated in U.S. Patent Application Publication No. 2011/0147186, wherein a sliding contact arrangement is disclosed in combination with a snapping arrangement. In such a design, there is no detrimental noise, nor is there any hysteresis. However, slide switches of this type cannot adequately carry medium or high currents and may have a relatively short life duration. One reason slide switches may be limited in this way is due to the fact that plastic and metal within the switch are in contact with one another when the switch changes state. Thus, medium-to-high currents may cause the plastic to melt, thereby tracking plastic onto the electrical contacts, causing high contact resistance and/or poor tactile feel during switch operation. Additionally, actuators used in slide switches may be sensitive to lateral forces, thereby limiting the placement and/or actuation options of the switches.
U.S. Pat. No. 6,753,489 discloses an electrical switch having a housing with a receiving portion, an actuation member comprising an actuating portion extending into the housing and arranged to be moved vertically between a pushbutton upper position and a pushbutton lower position, a pair of associated contact elements comprising a fixed contact element provided in the receiving portion, a movable contact element arranged facing the fixed contact element and that may come into contact with the fixed contact element for establishing a conductive switching way between the movable contact element and the fixed contact element, and an elastically deformable conductive blade in the form of a hairpin supported by the receiving portion. The blade includes a movable active branch.
In U.S. Pat. No. 6,753,489, the active branch of the hairpin-shaped blade is pivotally mounted with respect to the housing—around a horizontal pivotal axis—between a first active position in which a first switching way is established and a second switching way is interrupted, and a second active position in which the first switching way is interrupted and the second switching way is established. To provoke the pivotal movement of the active branch, the actuating portion is in the form of a cam acting on the other branch of the hairpin shaped blade.
According to such a design, the pivotal movement of the active branch tends to produce a loud snapping effect, and the two switching ways cannot be controlled independently. Also, in case of medium or high currents, the “floating” design of the blade does not permit electrical connection of the blade to the outside of the switch.
Accordingly, there is a need for a detect switch having a design that results in little or no hysteresis, that is relatively silent, and that may permit the carrying of medium or high currents.